Hydraulic circuit for a power transmission device

Abstract

A hydraulic fluid circuit for a power transmission device includes a first hydraulic circuit segment fluidly decoupled from a second hydraulic circuit segment. A hydraulic pump includes a first fluidic pumping element and a second fluidic pumping element. The first fluidic pumping element fluidly communicates with the first hydraulic circuit segment. The second fluidic pumping element fluidly communicates with the second hydraulic circuit segment. The first fluidic pumping element is controllable to a first pump operating point to achieve a preferred high fluidic flow rate in the first hydraulic circuit segment. The second fluidic pumping element is controllable to a second pump operating point to achieve a preferred high fluidic pressure in the second hydraulic circuit segment.

The invention claimed is: 
     
       1. Hydraulic fluid circuit for a torque transmission device, comprising:
 a first hydraulic circuit segment fluidly decoupled from a second hydraulic circuit segment; 
 a hydraulic pump comprising a first fluidic pumping element and a second fluidic pumping element, the first and second fluidic pumping elements comprising positive-displacement pumping elements having a common characteristic flow curve; 
 the first fluidic pumping element configured to fluidly communicate with the first hydraulic circuit segment; 
 the second fluidic pumping element configured to fluidly communicate with the second hydraulic circuit segment; 
 a first power source and a second power source selectively rotatably coupled to the first and second fluidic pumping elements; and 
 the first fluidic pumping element controllable to a first pump operating point of the common characteristic flow curve to fluidly communicate a hydraulic flow stream at a volumetric flowrate sufficient to achieve cooling and lubricating functions in the first hydraulic circuit segment coincident with the second fluidic pumping element controllable to a second pump operating point of the common characteristic flow curve to fluidly communicate a hydraulic flow stream at a hydraulic pressure sufficient to achieve activation of clutches in the second hydraulic circuit segment. 
 
     
     
       2. The hydraulic fluid circuit of  claim 1 , wherein the first power source comprises an electrically driven pump motor controlled to a preferred operating speed to operate the first fluidic pumping element at the first pump operating point and coincidentally to operate the second fluidic pumping element at the second pump operating point. 
     
     
       3. The hydraulic fluid circuit of  claim 2 , wherein the second power source comprises a mechanically driven power source. 
     
     
       4. The hydraulic fluid circuit of  claim 3 , further comprising a controllable one-way clutch configured to transfer torque from one of the electrically driven pump motor and the mechanically driven power source to both the first and second fluidic pumping elements. 
     
     
       5. The hydraulic fluid circuit of  claim 2 , wherein the hydraulic pump comprises a unitary dual element hydraulic pump comprising a single inlet port and first and second outlet ports fluidly coupled to the first hydraulic circuit segment and the second hydraulic circuit segment, respectively, said first and second fluidic pumping elements each comprising a positive displacement hydraulic pump element. 
     
     
       6. The hydraulic fluid circuit of  claim 1 , wherein the first hydraulic circuit segment further comprises a mechanism for monitoring volumetric flow. 
     
     
       7. The hydraulic fluid circuit of  claim 6 , wherein the mechanism for monitoring volumetric flow comprises a temperature sensor configured to monitor a temperature of an electric motor of the torque transmission device. 
     
     
       8. The hydraulic fluid circuit of  claim 1 , wherein the second hydraulic circuit segment further comprises a pressure sensor configured to monitor hydraulic pressure therein. 
     
     
       9. The hydraulic fluid circuit of  claim 1 , wherein the first hydraulic circuit segment fluidly decoupled from the second hydraulic circuit segment further comprises the first hydraulic circuit segment comprising the high flowrate circuit including a mechanism for monitoring volumetric flow therethrough and the second hydraulic circuit segment comprising the high pressure circuit including a pressure sensor configured to monitor hydraulic pressure therein. 
     
     
       10. Hydraulic fluid circuit for a power transmission device of a hybrid powertrain system, comprising:
 a first hydraulic circuit segment fluidly decoupled from a second hydraulic circuit segment; 
 a hydraulic pump comprising a first positive displacement fluidic pumping element and a second positive displacement fluidic pumping element configured to fluidly communicate respectively with the first hydraulic circuit segment and the second hydraulic circuit segment, the first and second positive displacement fluidic pumping elements employing commonly designed pump elements having common characteristic flow curves; 
 the first positive displacement fluidic pumping element controllable to a first pump operating point to achieve a preferred fluidic flow rate sufficient to achieve cooling and lubricating functions in the first hydraulic circuit segment; 
 the second positive displacement fluidic pumping element controllable to a second pump operating point to achieve a preferred fluidic pressure sufficient to achieve activation of clutches at a low fluidic flow rate in the second hydraulic circuit segment; 
 the first and second fluidic positive displacement pumping elements selectively rotatably coupled to one of an electric motor and a mechanical drive mechanism; and 
 the electric motor controllable to a preferred operating speed to operate the first positive displacement fluidic pumping element at the first pump operating point to achieve the preferred high fluidic flow rate at a low fluidic pressure at a volumetric flowrate sufficient to achieve cooling and lubricating functions and coincidentally to operate the second positive displacement fluidic pumping element at the second pump operating point. 
 
     
     
       11. The hydraulic fluid circuit of  claim 10 , wherein the hydraulic pump comprises a unitary dual element hydraulic pump comprising a single inlet port and first and second outlet ports fluidly coupled to the first hydraulic circuit segment and the second hydraulic circuit segment, respectively. 
     
     
       12. The hydraulic fluid circuit of  claim 7 , further comprising a controllable one-way clutch selectively rotatably coupling one of the electric motor and the mechanical drive mechanism to the first and second fluidic positive displacement pumping elements to coincidentally transfer torque to both the first and second positive displacement fluidic pumping elements. 
     
     
       13. Hydraulic fluid circuit for a torque transmission device, comprising:
 a first hydraulic circuit segment fluidly decoupled from a second hydraulic circuit segment; 
 a hydraulic pump comprising a first fluidic pumping element and a second fluidic pumping element, the first and second fluidic pumping elements employing commonly designed pump elements having common characteristic flow curves; 
 the first fluidic pumping element configured to fluidly communicate with the first hydraulic circuit segment; 
 the second fluidic pumping element configured to fluidly communicate with the second hydraulic circuit segment; 
 the first and second fluidic pumping elements selectively rotatably coupled to one of an electric motor and a mechanical drive mechanism; 
 the first fluidic pumping element controllable to a first pump operating point comprising a volumetric flowrate sufficient to achieve cooling and lubricating functions in the first hydraulic circuit segment coincident with the second fluidic pumping element controllable to a second pump operating point comprising a hydraulic pressure sufficient to achieve activation of clutches in the second hydraulic circuit segment. 
 
     
     
       14. The hydraulic fluid circuit of  claim 13 , wherein the electric motor is controlled to a preferred operating speed to operate the first fluidic pumping element at the first pump operating point and coincidentally to operate the second fluidic pumping element at the second pump operating point.